Healthy Weight during Pregnancy

The amount of food a woman needs during pregnancy depends on a number of things including her body mass index, or BMI, before pregnancy, the rate at which she gains weight, age and appetite. All pregnant women should eat a variety of nutrient-rich foods each day. It may also be necessary to take a vitamin and mineral supplement if recommended by a physician.

Research shows the risk of problems during pregnancy and delivery is lowest when weight gain is kept within a healthy range. Obesity during pregnancy can be risky for both mother and child, with some risks including gestational diabetes, gestational hypertension (high blood pressure), Cesarean delivery, birth defects and even fetal death.

Weight Gain Guidelines

Weight gain guidelines are based on a woman's BMI before pregnancy. The amount of weight gained depends on which category the pre-pregnancy BMI lands in:

• Underweight: BMI below 18.5
• Normal weight: 18.5 to 24.9
• Overweight: 25.0 to 29.9
• Obese: 30.0 and above

The weight ranges below are for a full-term pregnancy: 

• Underweight: 28 to 40 pounds
• Normal: 25 to 35 pounds
• Overweight: 15 to 25 pounds
• Obese: 11 to 20 pounds

For twins, the recommendations naturally go up: 

• Normal: 37 to 54 pounds
• Overweight: 31 to 50 pounds
• Obese: 25 to 42 pounds

There are no set guidelines for underweight BMI weight gain with twins.

Calorie Intake

In general, women who were at a healthy weight before becoming pregnant need between 2,200 calories and 2,900 calories a day when expecting. A gradual increase in calories as the baby grows is the best bet. Here is an overview of how calorie needs change during each trimester:

• The first trimester does not require any extra calories.
• During the second trimester, an additional 340 calories a day are recommended.
• For the third trimester, the recommendation is 450 calories more a day than when not pregnant.

Additional calories should come from nutrient-dense foods including lean protein, whole grains, low-fat or fat-free dairy, vegetables and fruit.

Physical Activity

Physical activity can help manage weight. The activity guidelines for pregnant women are for 150 minutes each week. An easy way to meet this goal may be to aim for 30 minutes of moderate exercise on most, if not all, days of the week. Make sure to talk with a doctor before starting or continuing any exercise routine while pregnant.